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Scientists of the Postharvest Technology Division (PTD) of Bangladesh Agricultural Research Institute (BARI) have developed an advanced machine for freeze-drying edible items.
The wastage of perishable things like fruits and vegetables can be prevented, maintaining quality, by using this technology. As the products retain their quality as per the International Food Standard (IFS), they can also be exported.
Freeze drying is a low-temperature dehydration technique that involves freezing the product and lowering pressure, removing the ice by sublimation. In contrast, the majority of traditional methods of dehydration use heat to evaporate water.
Using this technology, harvested products can be preserved to be sold in the local markets in the off-season. PTD scientists believe that freeze-dried products will play an important role in the commercialisation of agricultural products. Seasonal fruits like jackfruits, mango, pineapples, guava, papaya and many others can be preserved without reducing their quality or nutritional value. This technology can also be used to preserve processed food products. According to PTD, there is various existing preserving technology for edible items. PTD scientists have recently succeeded in producing and preserving processed food items from jackfruit.
Currently, many small-scale entrepreneurs are producing and marketing many processed food products including juice, jam, jelly, pickle, chutney, powder, chips, cutlets, cheese, ice cream, and frozen snacks. The demand for these items is gradually increasing.
These products can be preserved for a longer time using freeze-drying technology. Consumers will get a variety of safe and nutritious dried edible items available throughout the year.
Freeze-drying process
PTD’s Senior Scientific Officer Dr Ferdous Chowdhury, who led the team that developed the freeze dryer, said using the machine is relatively simple.
“We have to put previously frozen products in the machine for 48 to 72 hours. At a temperature of negative 50 degrees celsius, the water particles get evaporated,” he explained adding that the colour, shape and nutritional value of fruits and vegetables kept in the dryer remain almost unchanged and they become crisp.
The scientists have made jackfruit chips in the dryer by slicing them up and then adding 10-15 per cent sugar syrup before freezing them for 10-12 hours. The frozen fruit pieces undergo primary and secondary drying in a freezer drawer. In this process, water is extracted from the jackfruit pieces very slowly.
Since no oil or preservatives are used, the nutritional value remains healthy. The chips can be preserved for up to one month in airtight polythene packets, and about six months in 60-micron foil wrap.
Production cost
Freeze-dried fruit chips are popular in many countries including Malaysia, Singapore, Thailand, India, Vietnam, the Philippines, the United States, and the United Kingdom. The converted price of 100 grams of freeze-dried chips in those countries is around Tk 200-250.
In terms of the production cost of these chips in our country, buying a freeze dryer is the only major cost. However, the maintenance cost is relatively low.
According to PTD sources, importing commercial freeze dryers is expensive. However, the dryer can be manufactured locally with the technology developed by the PTC scientists.
What products can be freeze-dried
PTD officials said all kinds of fruits and vegetables can be freeze-dried and turned into chips using this method. As there is no wastage of nutrients, both chips and powdered products will be high quality.
“Chips and powdered spices can be made from all sorts of fruits and vegetables using a freeze dryer. As no chemicals or artificial colours are added, the food items will be safe for consumption,” said Dr Ferdous Chowdhury. All kinds of fruits and vegetables including raw, ripe and pickled mangoes, jackfruits, bananas, papayas, and pineapples can be dried in a freeze dryer thereby preventing huge wastage.
It should be noted that mango, jackfruit, banana, and pineapple are produced more in many parts of the country and due to surplus supply, a huge amount of it perishes and is wasted.
The export opportunities are good as there is demand for freeze-dried products abroad. According to BARI sources, osmodehydrated fruits have a market demand worth around Tk 500 crore abroad.
PTD’s Chief Scientific Officer Hafizul Haque Khan said the use of this technology is the need of the hour. “Initially, the machine might be expensive, but it is essential for various stages of processing of fruits and vegetables to produce safe food products of excellent quality. This will encourage entrepreneurs to invest and contribute significantly to earning foreign exchange,” he said.
